Sickle bar grinding machine



Dec. 27, 1955 KQRBER 2,728,170

SICKLE BAR GRINDING MACHINE Filed Feb. 19, 1952 3 SheetsSheet l 26 7' 25so. r'

ml fiu-nuwumlmum 45 1 "MN 4W ||mz mum IMMIIIIHHIT 45 79 34 4e j 38 76 3a6 3e 37 IN V EN TOR.

Jesse lfor'ber Dec. 27, 1955 J. H. KORBER 2,728,170

SICKLE BAR GRINDING MACHINE Filed Feb. 19, 1952 3 Sheets-Sheet 2 IN VENTOR.

Jesse Korber United States Patent SICKLE BAR GRINDING MACHINE Jesse H.Korber, Pawnee City, Nebr. Application February 19, 1952, Serial No.272,418

1 Claim. (Cl. 51-33) This invention relates to grinding apparatus, andparticularly to grinding apparatus adapted for the sharpening of thepointed or triangular-shaped teeth of sickles such as those used inmowers.

In mowers used for mowing hay and like crops, the cutting action is inmost instances obtained by a reciprocating sickle having a series oftriangularly shaped or pointed teeth extended forwardly from the forwardside of the sickle bar, and these triangular teeth are sharpened alongone edge thereof so that there is a sharp edge along each side of eachtooth and in a common plane so that these teeth may cooperate with thestationary elements that are afforded on the stationary elements thatare afforded on the stationary cutter bar of the mower. The normalgrinding or sharpening operation on sickle bars of the aforesaidcharacter is performed by holding the adjacent edges of two adjacentteeth in contact with a rotating grinding wheel that has angularsurfaces that conform with the desired shapeof the teeth and the edgethat is to be ground thereon, and it is well known that the desiredgrinding operation is quite difficult to perform in the field, or in theordinary farm workshop because of the weight of the sickle bar andbecause of the tendency of the metal to excessively heat when thegrinding operation is performed, thus producing what are known as burnson the edges that are being ground.

In view of the foregoing it is the primary object of the presentinvention to afford a grinding apparatus for sickles of the aforesaidcharacter whereby an ordinary unskilled worker may readily and easilygrind a good cutting edge on the teeth of such a sickle without dangerof burning or otherwise damaging the metal of the sickle.-

Other and more specific objects of the present invention are to affordsuch a grinder for sickles of mowers that is of such a character thatthe location of the work with relation to the grinding wheel may bereadily and easily accomplished, and in which the progress of the Workmay be readily checked by visual inspection that may be performed in aconvenient and easy manner.

Other and more specific objects of the present invention are to afford asickle grinder of the aforesaid character wherein the mechanism isadapted for ready and easy adjustment so that a proper and satisfactorygrinding operation may be attained despite progressive wear of thegrinding wheel, and to afford such a grinder wherein the relativemovements that are desired between the teeth of the sickle and thegrinding wheel are automatically attained, and in which such movementsare attained in such a way that the pressure between the work and thegrinding wheel is maintained at all times at a value which will insurethat a satisfactory grinding operation will be attained and damage tothe sickle bar will be avoided.

Another object of the present invention is to afford a sickle grinder ofthe aforesaid character wherein the mounting of the work in the machinemay be accomplished in a simple and expeditious manner, and it is alsoan object of this invention to aiford a sickle grinder which may, in avery simple manner, be converted into use in sharpening tools and knivesand for other general grinding purposes that may be encountered in afarm workshop.

Other and further objects of the present invention will be apparent fromthe following description and claim and are illustrated in theaccompanying drawings which, by way of illustration, show a preferredembodiment of the present invention and the principle thereof and what 1now consider to be the best mode in which I have contemplated applyingthat principle. Other embodiments of the invention embodying the same orequivalent principle may be used and structural changes may be made asdesired by those skilled in the art without departing from the presentinvention.

In the drawings:

Fig. 1 is a front perspective view of a sickle grinder embodying thefeatures of the invention;

Fig. 2 is a plan view thereof;

Fig. 3 is a vertical sectional view taken along the line 33 of Fig. 2;

Fig. 4 is an enlarged fragmental portion of Fig. 2;

Fig. 5 is an enlarged sectional view taken along the line 55 of Fig. 3;

Figs. 6 and 7 are enlarged front elevational and top plan viewsrespectively showing the relation of the sickle and the grinding wheel;and

Fig. 8 is an enlarged portion of Fig. 3 showing the sickle-grindingwheel relation.

For purposes of disclosure the invention is herein illus trated asembodied in a sickle grinder 20 that comprises a bed 21 having anelongated mounting bar 22 arranged along its forward edge; and on themounting bed 21, a grinding wheel 25 is mounted for rotating movementabout a horizontal axis that is parallel to the front mounting bar 22and for movement in a generally up and down direction so that a grindingrelationship of the wheel 25 to a sickle bar 26 may be varied, thesickle an ordinary grinder for brought into the desired grindingrelationship with respect to the grinding wheel 25.

The mounting bed 21 in the present instance is afforded as a part of atable structure, having two front legs 29 and a single rear leg 30extended downwardly therefrom so that the bed may be supported in themanner of a table for floor mounting. As will be evident in Figs. 6 and7 of the drawings, the sickle 26 is made up in the conventional mannerso as to afford pointed teeth 26T which are ground along each of theirforward edges so as to define cutting edges 26C that are disposed in acommon plane defined by the surfaces on one face of the teeth 26T. Theedges 26C of the teeth 26T, of course, are ground to substantially apredetermined cutting angle, and this is accomplished through the use ofa grinding wheel such as the grinding wheel 25 which has angularlyrelated grinding surfaces 25R and 25L, as is customary in grindingwheels for this particular purpose. As will be hereinafter pointed outin detail, the sickle 26 is mounted on mounting means carried on thefront mounting bar 22 so that the sickle may be shifted laterally and bya rocking movement into and out of a grinding relationship with respectto the grinding wheel 25, and also to enable the sickle bar to beshifted in an endwise direction to bring different ones of the V-shapedspaces between the teeth into alignment with the center of the grindingwheel 25.

As herein shown, the supporting bed 21 as well as the leg structures areformed from angle iron sections, and these sections are so arranged thatthey may be cut and punched to the proper form, and after being shippedto the user, may be readily assembled to afford the desired supportstructure for the present machine. Thus, the bed '21 is formed on threesides by a single angle iron piece that has a rear bar or section 21A,Fig. 2, and two side sections 21L and 21R, one flange of the angle ironbeing appropriately notched as at 21N at both ends of the rear member21A and being bent so that the side members 21L and 21R diverge slightlyin a forward direction. The forward ends of the side members 21L and 21Rare disposed beneath the horizontal flange of the front mounting bar 22,which is, of course, formed from an angle iron which in the presentinstance is somewhat larger in cross-sectional size than the other angleiron members, and the forward ends of the members 21L and 21R areconnected to the front mounting rail 22 by means of bolts 33. The upperends of the front legs 29 have their forward flanges connected to thefront mounting bar by means of bolts 34, while the upper end of the rearleg is connected to the rear member 21A by means of a bolt 35. The twofront legs 29 have angle braces 36 extended therefrom upwardly andtoward each other and connected to the vertical flange of the front bar22, the connections at the opposite ends of the braces 36 beingaccomplished by bolts 37. Similarly, braces 38 are extended angularlybetween the front legs 29 and the adjacent side members 21L and 21Rrespectively, and the connection at opposite ends of these angle bracesis afforded by means of bolts (not shown). The rear leg is held in itsproper relationship by stretcher members 40 connected by bolts 41 to therear leg 30 and connected by bolts 42 to the respective front legs 29.Thus, a relatively rigid table structure is afforded, the top of whichconstitutes the bed 21 upon which the mounting and operating elements ofthe present apparatus are disposed.

The mounting for the sickle bar 26 is afforded by means including threeupstanding lugs 45 afforded on the upper or horizontal flange of thefront mounting bar 22, and these lugs are equally spaced so that onesuch lug is located at each of the opposite ends of the bar 22, whilethe third lug 45 is located substantially centrally of the bar 22, and amounting rod 46 is extended through the several lugs 45 in a stationaryrelationship to serve as a slidable and pivotal support for a pair ofclamps 50. One of these clamps 50 is mounted on the rod 46 on each sideof the central supporting lug 45, and these clamps may move with asliding action longitudinally along the rod 46, and may rock to alimited extent about the axis of the rod 46. Each clamp 56 includes apair of opposed jaws 58F and 59R that are spaced apart and are adaptedto receive the back or bar portion of the sickle and to clamp the sameby means of a clamping screw 50C that extend through the front jaw 50Fand may be tightened to press and clamp the bar against the rear jaw50R. Each of these clamp members 50 has a forwardly extending tailportion SQT at its front lower end, so that when the clamp '50 rocks inwhat may be termed a forward direction, the tail SOT will strike thecorner of the angle bar 22 and act as a stop to limit the forwardtilting movement of the clamp, and this relationship is utilized tolimit the forward rocking movement of the sickle shown in dotted outlinein Fig. 8 to a position wherein the cutting edges are spaced from thegrinding wheel 25 and are located so that they may be readily inspectedby the user.

The grinding wheel 25 is supported on the bed 21 by means including arelatively long and flat mounting plate 60 that extends between andrests upon the front bar 22 and the rear member 21A of the bed, and itwill be observed that this mounting plate has a slot 685, Fig. 4,extending rearwardly from its front edge for purposes that will appearhereinafter. Also, it will be noted that on each side of the forward endof this slot 60S, smaller elongated bolt-receiving slots 61 are providedthrough which fastening bolts 62 may be extended downwardly through thehorizontal flange of the front bar 22 for clamping the forward end ofthe mounting plates 60. in position with respect to the front bar 22.Similarly, at

the rear edge of the mounting plates 66, there is an elongated slot 63extending in a front to rear direction and through which a clamping bolt64 may extend into the horizontal flange of the rear member 21A, thus tofix the rear end of the mounting plate 60 in position on the bed 21.

In providing for the desired up and down movement of the grinding wheel25, this grinding wheel is mounted by means of the usual wheel-mountingstructure on one end of a rotatable shaft 65 that is carried in abearing 66 that is afforded along the forward end of a relatively wideand fiat mounting or rocking arm 67, the rear end portion of the rockingarm 67 having an enlarged bearing structure 68 formed thereon throughwhich a mounting shaft 69 extends. This mounting shaft 69 is supportedstatiouarily in a horizontal position and parallel to the forward rod 46by means such as a pair of upstanding mounting lugs 73 that are formedintegrally with the plate 60. The mounting lugs 79 are so located thatthe rocking arm 67 is disposed directly over the slot 608 that is formedin the mounting plate 60, and the rocking arm 67 has a slot 678 formedtherein to facilitate the connection of an actuating means to therocking arm 67. Thus, along the opposite sides of the slot 67S and onthe lower surface of the rocking arm 67, a pair of downwardly extendinglugs 67L are formed and the upper end of a link 72 is pivoted betweenthese two lugs 67L by a pin 73. The lower end of the link 72 is mountedin surrounding relationship toan eccentric 7415 that is fixed to arelatively large gear 74 that is rotatively supported on a shaft 75 in agear housing 76 that projects downwardly from the lower face of themounting plate 60 just to the right of the slot 608 as viewed in Fig. 5of the drawings. The gear housing 76 also serves as a housing for arelatively small pinion 77 that is meshed with the gear 74 the pinion 77being fixed on a drive shaft 78 that extends through the gear housing76. The drive shaft 78 has a relatively large V-belt pulley 79 fixedthereto, whereby the shaft 78 may rotate the gears 77 and 74, and thelink 72, and the rocking arm 67 may be caused to move up and downthrough a limited stroke that is determined by the eccentricity of theeccentric 74E. The grinding wheel 25 as herein shown is mounted on theleft hand end of the shaft 65, as viewed in Fig. 5 of the drawings, andfor purposes that will appear hereinafter, a conventional grinding wheel125 is mounted on the opposite end of the shaft 65. Preferably a guard25G is mounted on the arm 67 so as to overhang a portion of the grindingwheel 25 as shown in Figs. 1, 3 and 4. Between the conventional grindingwheel 125 and the adjacent end of the bearing sleeve 66, a relativelysmall V-belt pulley 82 is fixed on the shaft 65, and the desiredoperating or rotating movements are imparted to the shafts 65 and 78 bymeans that are connected to the aforesaid V-belt pulleys 79 and 82.

In the present instance, the drive means is supported on the rearportion of the mounting plate 60, rearwardly of the lugs 70, and thedriving means may take any conventional form in accordance with thepower facilities at the particular farm where the sickle grinder is tobe used. In the present instance an electric motor 85 is shown as boltedto the mounting plate 60, and a V-belt pulley 86 is provided on theextreme end of the motor shaft and is connected by means of a V-belt 87to the large belt pulley 79 so as to drive the eccentric 74E. Another V-belt pulley 88 is also fixed onthe motor shaft, and this is connected bymeans of a V-belt 89 to the V-belt pulley 82 that is fixed on the shaft65. It will be observed that the axes of the motor shaft and the rockingplate 67 are so related to the path of movement of the shaft 65 that thebelt 89 maintains a proper tension throughout the entire reciprocatingor up and down stroke of the grinding wheel.

With the structure that has thus far been described, the grinding wheel25 will be constantly rotated, and

B! u the grinding wheel will also move up and down at a relatively slowrate between the full line position and the dotted line position shownfor the grinding wheel in Fig. 8 of the drawings. It is important tonote the relationship between the grinding wheel 25 and itsreciprocating stroke and the work holders or clamps 50 and the sickleteeth 26T. Thus it will be noted that the axis of the rod 46 upon whichthe workholding clamps 50 are adapted to rock is disposed a substantialdistance forwardly or to the right in Fig. 8 with respect to the forwardedge of the grinding wheel 25, and the form of the rear jaws 50R is suchthat when a sickle is clamped in position in the clamps 50, the sickle26 and the clamps 50 must be rocked to what may be termed a forwardover-center position such that the weight of the sickle is disposedrearwardly or to the left in Fig. 8 with respect to the axis of themounting rod 46. The weight of the sickle 26 is thus eflective to tendto rock the clamps and the sickle in a counter-clockwise direction, Fig.8, or in other words toward an engaging relationship with respect to thegrinding wheel. This eccentricity of the center of gravity of the sickleand its mounting structure is so arranged, as shown in Fig. 8, that asufficient force will be effective upon the sickle to hold the teeththereof in engagement with the angular surfaces 25L and 25R of thegrinding wheel, and yet this force is sufiiciently low to insure thatthe sickle will not be excessively heated and burned in the course of anormal grinding operation.

The relationship between the sickle and the grinding wheel 25 is suchthat when the grinding wheel is in its lower position, it will force thesickle through a rocking movement to the right or in a clockwisedirection, Fig. 8, to the full line position shown in Fig. 8, and inthis relationship, the grinding wheel is elfective to grind thelowermost portions of the edges 26C of the sickle teeth. Then, when themotion of the grinding wheel 25 reverses and the grinding wheel movesupwardly toward its dotted line position of Fig. 8, the sickle 26 willrock gradually to the left-hand dotted line position of Fig. 8, and thismovement progresses as the wider or upper portions of the V-openingengage with the sickle, and when the grinding wheel 25 has reached itsuppermost position, the wheel will be grinding the portions of the edges26C that are adjacent to the points of the teeth 26T.

In the use of the present apparatus, it is found that the location ofthe work or the sickle 26 in a longitudinal sense with respect to thegrinding wheel 25 need not be accurately established by the operator, itonly being necessary for the operator to move the sickle endwise intothe approximate position required, after which the operator may againrock the sickle toward the grinding wheel so as to allow the same tobear against the grinding wheel due to the action of gravity as abovedescribed. Then, in the up and down reciprocating movements of thegrinding wheel, the grinding wheel may initially be grinding against butone of the edges 26C of the particular V- shaped space that has beenselected, but it is found in practice that in the first one or tworeciprocations of the grinding wheel, the forces exerted on the sickleare suificient to cause the sickle and its mounting clamps 50 to movelongitudinally along the mounting rod 46 until the teeth that are to beground are centered upon and are both engaged with the grinding wheel inthe proper relationship. The operator then allows the grinding operationto progress for a short time, after which the operator may rock thesickle to its retracted position illustrated by the right-hand dottedline relationship shown in Fig. 8 of the drawings, and when the sicklehas been thus retracted, the operator may look downwardly onto theground edges of the sickle to determine whether or not the grindingoperation has progressed to a sufiicient extent. If the grinding hasbeen completed as shown by such inspection, the operator may shift thesickle another tooth space in one direction or the other and establishthe grinding relationship in respect to other teeth as hereinabovedescribed.

It will be observed that the range of longitudinal movement of theclamps 50 is limited by the central lug and by the length of the rod 46to substantially one-half the length of the normal sickle that has beenillustrated particularly in Fig. 1 of the'drawings, and this conditionis taken care of in practice by so mountingthe sickle in the clamps 50that the teeth throughout about one-half of the sickle may be ground inthe normal range of movement of the clamps along the rod 46, andthereafter, the clamps are shifted and the workpiece or sickle is againput in place in the clamps so that the work may be moved through thebalance of the necessary range along the grinding wheel.

It should be observed that when the wear of the grinding wheel resultsin improper grinding of the lower ends or roots of the teeth 261, thiscondition may be readily corrected by adjustment of the plate in aforward direction on the bed 21.

From the foregoing description it will be apparent that the presentinvention enables the grinding of sickles to be accomplished quickly andeasily by an ordinary unskilled worker, and this is accomplished in sucha way that the danger of damage to the sickle is avoided. It will alsobe evident that the present invention is of such a character that itsimplifies the location of the work with respect to the grinding wheel,and the progress of the grinding operation may be readily checked in asimple and easy manner.

It will also be apparent that the present invention enables the sickleto be ground without the necessity for the operator to support theweight of the sickle, and under the present invention the necessaryforce between the grinding wheel and the sickle is automaticallyapplied, in the present instance by gravity, so that the danger ofbreaking or otherwise damaging the sickle is avoided.

It will also be evident that the present sickle grinder is of particularutility in that the user may, when an ordinary grinding operation is tobe performed, remove the belt 87 so that the grinding wheel shaft willremain stationary at the desired elevation and the worker may thenperform the desired conventional grinding operation.

Thus, while I have illustrated and described the preferred embodiment ofmy invention, it is to be understood that this is capable of variationand modification.

I claim:

A sickle grinder of the character described adapted for grinding theadjacent edges of adjacent teeth on a sickle, the combination of asupporting frame having an elongated horizontal front supporting bar anda parallel rear supporting bar spaced rearwardly from said frontsupporting bar, an elongated mounting rod mounted on and in upwardlyspaced relation to said front bar, a pair of sickle clamps mounted onsaid rod for rocking movement on and about the horizontal axis of saidrod and for free sliding movement throughout a substantial rangelongitudinally of said rod, a mounting plate mounted on and extendedbetween said front and rear bars in a horizontal position for limitedadjustment toward and away from said mounting rod, a rocking arm mountedon and above said mounting plate on a horizontal axis spaced asubstantial distance rearwardly from said front support bar, a grindingwheel shaft rotatably mounted on the forward end of said rocking arm andhaving a grinding wheel fixed on one end thereof, such grinding wheelhaving a V-shaped working surface adapted for grinding the adjacentedges of adjacent sickle teeth, driving means mounted on the upper faceof said mounting plate and having a driving connection with saidgrinding wheel shaft for constantly rotating said shaft and saidgrinding wheel, a gear housing extended downwardly from said plate andhaving a rotatable member therein, means affording an eccentricconnection between said rotatable member and said rocking arm, and meansincluding a driving belt Refgrences Cited in the file of this paxen-tUNlTED STATES PATENTS 567,638 Clizbe Sept. 15, 1896 623,683 Neuens et a1Apr. 25, 1899 665,328 Johnston 5 Jan. 1, 1901 8 Neuens V 51111 24, 1-992Nixon Apr 2 1.904 Pneuman May 10, 1904 Brown et a1. Apr. 4, 193,3vBend-a July 18, 1-939 Rainbolt et a1. Sept. 27, 1949 Harrell Aug. 8,1950 Rinne Jan. 15, 1952 'Webber Jan. 29, 1952

